ALTERED REGULATION OF INSULIN-LIKE GROWTH-FACTOR BINDING PROTEIN-I INPATIENTS WITH POLYCYSTIC-OVARY-SYNDROME

OBJECTIVE: Insulin-like growth factor (IGF-I) action is influenced by circulating as well as tissue levels of its binding proteins. Because sevum IGF binding protein-1 (IGFBP-1) levels have been found to be dec reased in patients with polycystic ovary syndrome (PCOS), we tested th e hypothesis that regulation of IGFBP-1 secretion may be different inp atients with PCOS compared with normal women. METHODS: We studied 15 n ormal ovulatory women and 15 women with PCOS of similar age (21 +/- 1 and 22 +/- 1 years, respectively). All subjects were studied after an overnight fast between days 5-8 after spontaneous or progestin-induced menses. Perturbations included the administration of insulin intraven ously, maintenance of a euglycemic clamp, and, in a subsequent cycle, the administration of a long-acting somatostatin analogue (octreotide, 100 mu g) given subcutaneously. Blood samples were collected before t reatment, every 15 minutes for 6 hours after insulin, and every 30 min utes for 3 hours after octreotide administration. Serum levels of IGF- I, IGFBP-1, IGFBP-3, and insulin were measured by specific immunoassay s. RESULTS: Compared with the controls, patients with PCOS had signifi cantly higher insulin levels, similar IGF-I and IGFBP-3 levels, and si gnificantly lower IGFBP-1. Insulin did not change serum IGF-I levels i n either group, although a significant decrease in IGFBP-1 levels occu rred in normal women but nor in patients with PCOS. Octreotide treatme nt also did not change serum IGF-I levels in either group, but serum i nsulin levels decreased significantly and IGFBP-1 levels increased sig nificantly in both groups; this response was significantly greater in controls. CONCLUSION: Our data ave compatible with the notion that reg ulation of IGFBP-1 is altered in women with PCOS and that several fact ors may be involved.